/*

 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package gc.z;

/*

 * @test TestHighUsage

 * @requires vm.gc.Z & !vm.graal.enabled

 * @summary Test ZGC "High Usage" rule

 * @library /test/lib

 * @run main/othervm gc.z.TestHighUsage

 */

import java.util.LinkedList;

import jdk.test.lib.process.ProcessTools;

public class TestHighUsage {

    static class Test {

        private static final int K = 1024;

        private static final int M = K * K;

        private static final long startAt = 16 * M;

        private static final long spikeAt = 4 * M;

        private static volatile LinkedList<byte[]> keepAlive;

        private static volatile Object dummy;

        public static void main(String[] args) throws Exception {

            System.out.println("Allocating live-set");

            // Allocate live-set

            keepAlive = new LinkedList<>();

            while (Runtime.getRuntime().freeMemory() > startAt) {

                while (Runtime.getRuntime().freeMemory() > startAt) {

                    keepAlive.add(new byte[128 * K]);

                }

                // Compact live-set and let allocation rate settle down

                System.gc();

                Thread.sleep(2000);

            }

            System.out.println("Allocating garbage slowly");

            // Allocate garbage slowly, such that the sampled allocation rate on

            // average becomes zero MB/s for the last 1 second windows. If free

            // memory goes below the spike limit we induce an allocation spike.

            // The expected behavior is that the "High Usage" rule kicks in before

            // the spike happens, avoiding an "Allocation Stall".

            for (int i = 0; i < 300; i++) {

                final long free = Runtime.getRuntime().freeMemory();

                System.out.println("Free: " + (free / M) + "M");

                if (free > spikeAt) {

                    // Low allocation rate

                    dummy = new byte[128 * K];

                } else {

                    // High allocation rate

                    dummy = new byte[8 * M];

                }

                Thread.sleep(250);

            }

            System.out.println("Done");

        }

    }

    public static void main(String[] args) throws Exception {

        ProcessTools.executeTestJvm(new String[]{ "-XX:+UnlockExperimentalVMOptions",

                                                  "-XX:+UseZGC",

                                                  "-XX:+UnlockDiagnosticVMOptions",

                                                  "-XX:-ZProactive",

                                                  "-Xms128M",

                                                  "-Xmx128M",

                                                  "-XX:ParallelGCThreads=1",

                                                  "-XX:ConcGCThreads=1",

                                                  "-Xlog:gc",

                                                  Test.class.getName() })

                    .shouldNotContain("Allocation Stall")

                    .shouldContain("High Usage")

                    .shouldHaveExitValue(0);

    }

}